Evolution and taxonomy of the wild species of the genus Ovis (Mammalia, Artiodactyla, Bovidae)

摘要

New insights for the systematic and evolution of the wild sheep are provided by molecular phylogenies inferred from Maximum parsimony, Bayesian, Maximum likelihood, and Neighbor-Joining methods. The phylogeny of the wild sheep was based on cytochrome b sequences of 290 samples representative of most of the sub-species described in the genus Ovis. The result was confirmed by a combined tree based on cytochrome b and nuclear sequences for 79 Ovis samples representative of the robust clades established with mitochondrial data. Urial and mouflon, which are either considered as a single or two separate species, form two monophyletic groups (O. orientalis and O. vignei). Their hybrids appear in one or the other group, independently from their geographic origin. The European mouflon O. musimon is clearly in the O. orientalis clade. The others species, O. dalli, O. canadensis, O. nivicola, and O. ammon are monophyletic. The results support an Asiatic origin of the genus Ovis, followed by a migration to North America through North-Eastern Asia and the Bering Strait and a diversification of the genus in Eurasia less than 3 million years ago. Our results show that the evolution of the genus Ovis is a striking example of successive speciation events occurring along the migration routes propagating from the ancestral area.